Optical transceiver with a pluggable function

ABSTRACT

The optical transceiver of the present invention is one type of the pluggable transceiver that is inserted into/extracted from the cage in the host system. The transceiver includes the OSA (Optical Sub-Assembly) unit, which shows the optical function, and the body unit installing the electronic circuit. The OSA unit includes the receptacle member, the tab plate and transmitting/receiving sub-assemblies. The body unit includes the base installing the circuit board, the heat conducting plate to conduct heat generated by the IC on the substrate to the rear end of the transceiver, the supplementary substrate, the supporting plate, and the cover for putting these components therein. In the present transceiver, the heat is effectively conducted to the rear end thereof the heat conducting plate, besides, the tab plate, the heat conducting plate, and the supporting plate are made only by cutting, bending and tapping without any welding and gluing. Therefore, the present invention may provide an optical pluggable transceiver with superior heat dissipating function by cost saved configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patent application Ser. No. 11/242,148, filed Oct. 4, 2005, which claims the benefits of U.S. provisional patent applications Ser. No. 60/615,587, filed Oct. 5, 2004, Ser. No. 60/620,325, filed Oct. 21, 2004, Ser. No. 60/632,937, filed Dec. 6, 2004, and Ser. No. 60/652,846, filed Feb. 15, 2005, which are incorporated herein by reference. The present application also claims priority from JP2006-014602 filed in Japan on Jan. 24, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a structure of a pluggable optical transceiver, and a method for manufacturing the same.

2. Related Prior Art

The pluggable transceiver 1 (hereinafter denotes as transceiver) shown in FIG. 1A is used by being inserted into the cage 2 provided on the circuit board of the host system. The transceiver 1 inserted into the cage 2 is shown in FIG. 1B. On the bottom of the cage 2 is formed with stud pins 2 c, and the cage 2 is installed on the circuit board of the host system by soldering these stud pins 2 c to the circuit board so as to expose the opened end 2 a from the face panel of the host system. In the inner end of the cage 2 is provided with an electrical connector 2 b such that the each electrode of the connector 2 b is in contact to, or soldered to the wiring pattern on the circuit board. By inserting the transceiver 1 into this cage 2, the electrical plug configured in the rear end of the transceiver 1, mates with this connector 2 b within the cage to enable the transceiver 1 to communicate with the host system. In FIG. 1B, the host system, the circuit board and the face panel thereof, are omitted. Moreover, to configure the electrode of the plug makes the transceiver 1 so-called hot-pluggable, by which the transceiver 1 is able to insert into/remove from the cage 2 as the host system is powered on.

The cage 2, as shown in FIG. 1B, is a metal box with one end 2 a being opened. Although a tip of the tab plate protrudes from the cover 23 of the transceiver 1, when the transceiver 1 is set within the cage 2, this tab plate 14 is also set within the cage 2 as the tip thereof coming in contact to the inside of the cage 2. Moreover, a plurality of fins 2 d extends outward in the front portion thereof to surround the opened end 2 a. When the cage 2 is installed on the circuit board of the host system, these fins 2 a come in electrically contact to the face panel to shield the transceiver 1 and the host system.

Some multi-source agreements (MSA) rule the outer dimension and the electrical specification for such pluggable transceiver. The normal operation can be ensured as long as the transceiver follows the agreements, even when such transceiver is provided from the extraordinary manufacturer. Further, since the agreement rules the outer dimension, the insertion/extraction of the transceiver is also ensured.

However, the cage itself is made of a thin metal plate to deform in ease by an extra force, even by the insertion/extraction of the transceiver to the cage. The tab plate is necessary to come in reliable in contact to such deformed cage. The tab plate is provided to secure the EMI (Electro-Magnetic Interference) shield function for the transceiver 1. Recently, the operational speed, i.e., the clock speed of the transceiver reaches and exceeds 1 GHz. In such high speed operation, the high frequency signal is firmly prevented from leaking from the equipment. The tab plate is necessary to come in contact to the physically deformed cage 2.

Another subject under such high operational speed is that, the active devices, such as ICs and transistors, installed within the transceiver becomes necessary to be provided with large current to operate in a high frequency band, which results in the further heat being generated in the devices and the request to provide a further effective mechanism for the heat dissipation. However, the transceiver is unable to touch the case thereof in tight to the cage because the pluggable transceiver is inherently assumed to be inserted into/extracted from the cage 2. Tightly and firmly touching to the cage disturbs the smooth insertion/extraction of the transceiver.

Further, the transceiver comprises of three parts, namely, subassemblies to covert an optical signal to an electrical signal, or an electrical signal to an optical signal, a body portion installing the electronic circuit and an optical receptacle, and an mechanism to engage the transceiver with the cage. The U.S. Pat. No. 6,349,918 has disclosed the engaging mechanism using a bail and an actuator. Rotating the bail in front of the optical receptacle, one end of the bail pushes up the actuator, accordingly, the other end of the actuator is pressed down to disengage with the cage because the actuator moves in the seesaw motion. The other United States patent application published as US-2003/0142917A has also disclosed a similar mechanism.

Recently, one application has been proposed that, a plurality of transceivers is densely arranged to configure an optical hub system for the optical communication. For example, to arrange the transceiver, the cross section of which is about 1 centimeter square, by 16 pieces in horizontal and two to four in vertical forms the hub system providing 32 to 64 optical channels. In such system, when the target transceiver is to be removed from the cage as the other cages surrounding the target transceiver are set with transceivers each providing an optical cable, the bail of the target transceiver is hard to rotate because the neighbor transceivers and their optical cables prevent from touching thereto, which prohibit the target transceiver from being extracted from the cage.

Therefore, the present invention is to provide a new structure of the optical pluggable transceiver based on the MSA and a method for manufacturing the same. The transceiver according to the present invention, not only satisfies the MSA standard, but also ensures the reliable shielding by effectively covering the body of the transceiver and stably touching body to the cage, provides the effective heat dissipation mechanism from the devices to the outside thereof, and provides a disengaging mechanism with the cage even a plurality of transceivers with the optical cable is densely arranged.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a structure of a pluggable optical transceiver that is inserted into or extracted from the cage of the host system. The cage exposes one end portion thereof from the face panel of the host system to receive the pluggable transceiver, and provides an electrical connector in the other end. The connector is mounted on the circuit board of the host system.

The optical transceiver of the present invention comprises an optical assembly unit and a body unit. The former unit includes a receptacle member, a tab plate and an optical sub assembly. On the other hand, the latter unit includes a substrate, a base, a heat conducting plate, and a cover. The receptacle member may be made of resin and configured with an optical receptacle for receiving an optical connector with an optical fiber. The tab plate is made of metal and engaged with the receptacle member. The optical subassembly, which may include a transmitting optical subassembly (TOSA) and a receiving optical subassembly (ROSA) when the transceiver performs a full duplex communication, includes a semiconductor optical device that is optically coupled with the optical fiber within the optical connector. This optical subassembly is installed on the receptacle member.

The substrate mounts an electronic circuit and mates with the electronic connector within the cage. The base, which is made of metal, installs the substrate and is engaged with the optical assembly unit. The heat conducting plate, which is also made of metal, is in contact to the electronic circuit mounted on the substrate. This heat conducting plate is engaged with the base. The cover, which is also made of metal, puts the base, the heat conducting plate, the optical subassembly and the substrate therein.

One feature of the transceiver according to the present invention is that these metal tab plate, the metal base, the metal heat conducting plate, and the metal cover are, although the materials may be different form each other, all made from a metal plate by cutting, bending, and tapping without welding and gluing. Due to this configuration, not only the material cost of the transceiver may be reduced but also the manufacturing process thereof may be simplified, thereby reducing the cost thereof.

The receptacle member of the invention may include first to third portions. The first portion is configured to form the optical receptacle. The second portion forms a first projection in an outer side thereof. The third portion forms a second projection in an outer side thereof. The tab plate may include first and second portions. The first portion of the tab plate forms a latch tab engaged with the first projection of the receptacle member. The second portion is folded twice to form a U-shaped cross section, and the third portion of the receptacle member is put between this U-shape portion.

Thus, the tab plate may be assembled with the receptacle member only by inserting the third portion of the receptacle member into the second portion of the tab plate and by engaging the latch tab of the tab plate with the first projection of the receptacle member. Therefore, the manufacturing cost of the transceiver may be reduced. The tab plate may also provide a socket to receive the center post of the base.

The base may include a bottom, a pair of sides extending from the base, and a center post also extending from an end of the bottom. The receptacle member may include a pair of sides forming a second projection and a center partition for forming a cavity to install the optical subassembly therein. The receptacle member may further include a plateau behind the center partition. This plateau abuts against the center post of the base.

The side of the base may include a support with an opening. This opening engages with the second projection of the receptacle member. Thus, the base and the receptacle member of the present invention may be assembled to each other by inserting the center post of the base into the socket of the tab plate, abutting the tip thereof against the plateau of the receptacle member and engaging the second projection of the receptacle member with the opening of the base, without any screwing. Therefore, the manufacturing cost of the transceiver may be reduced. Moreover, the engagement of the base with the receptacle member and the tab plate may be carried out in compensate, that is, the former engagement of the center post to the socket is carried out between the convex in the base and the concave in the receptacle member, while, the latter engagement between the projection in the receptacle member and the opening in the base is carried out between the concave in the base and the convex in the receptacle member, which may strengthen the engagement.

The base of the present invent may include a first portion for mounting the substrate and a second portion for engaging with the heat conducting plate. The second portion may include a pair of coupling surface with a slit therebetween. Each coupling surface has firs and second fitting surfaces bent downward along a longitudinal direction of the transceiver. On the other hand, the heat conducting plate may include first to fourth portions. The first portion is in contact to the electronic circuit on the substrate. The second portion is in contact to the coupling surfaces of the base. The third and fourth portions of the heat conducting plate each includes a surface fitted to the first and second fitting surface of the coupling portion.

The heat conducting plate may further include, in the second portion thereof, a pair of fitting tabs and a spacer tab both bent downward. The spacer tab has a width slightly larger than that of the slit between the coupling portions of the base. On the other hand, the base may further include, in the coupling surface thereof, a pair of tabs each bent downward. These tabs are in contact to the fitting tab of the heat conducting plate. Thus, the coupling surface of the base is put between the spacer tab and the fitting tab of the heat conducting plate. That is, the spacer tab presses the coupling surface of the base outward, while, the fitting tabs abut against the tab of the coupling surface to press inward. Thus, the base and the heat conducting plate of the present invention is assembled only by fitting to each other without no screwing, which may simplify the manufacturing process and reduce the cost thereof.

The optical transceiver of the present invention may further include a supplementary substrate to mount a supplementary circuit. The supplementary substrate, electrically connected to the primary substrate with a flexible printed circuit board, is mounted on the heat conducting plate so as to fold the flexible printed circuit board. The flexible printed circuit board provides a projection that is set behind the coupling portion of the base. Since this configuration hides the edge of the flexible printed circuit board by the base, the cover does not hook the board when the cover is set to the body unit.

The optical transceiver may further include a supporting plate to position the supplementary substrate. That is, the heat conducting plate may further include, in the first portion thereof, a supporting post bent upward. On the other hand, the supporting plate may include first to fourth portions. The first portion is inserted under the heat conducting plate and has a pair of legs each having a step inserted into the notch of the supplementary substrate. The second portion includes a surface abutted against the side of the supporting post. The fourth portion has a pair of legs each having a step engaged with the step formed in the end of the supplementary substrate. The third portion that connects the second portion with the fourth portion is configured with an arched shape protruding outward. When the cover is set to body unit, the cover presses the third portion of the supporting plate, accordingly, the supporting plate presses down the supplementary substrate. Thus, the supporting plate of the present invention may be assembled with the supplementary substrate and the heat conducting plate only by fitting without any screwing, which may also reduce the manufacturing cost.

The optical transceiver of the invention may further include a bail and an actuator for providing the releasing mechanism of the transceiver from the cage. The optical receptacle member may further provide structures to assemble these bail and actuator. That is, the receptacle member may provide third projections in both outer sides thereof, and a center projection and a pair of beaked hooks in the bottom surface thereof. The bail is configured with a pair of legs each having an opening for receiving the third projection and a bridge portion connecting these legs. The actuator has a hollow for receiving the center projection, an axis that is fitted into the beaked hook, and an engaged projection in a tip thereof. To rotate the bail with the third projection as a center of the rotation causes a seesaw motion of the actuator around the axis thereof, which draws the engaged projection inward to release the optical transceiver from the case. Thus, the present transceiver assembles with the bail and the actuator only by fitting, which reduces the manufacturing cost.

Moreover, the actuator of the present transceiver includes a pressing surface in the end opposite to the side where the engaged projection is formed in the tip thereof. To press the pressing surface of the actuator causes a rotational moment to the bail, which enables to release the optical transceiver from the cage.

Still further, the bridge portion of the bail may provide a color code to identify an emission wavelength of the transceiver. When the transceiver is applied to the wavelength division multiplex (WDM) system, the emission wavelength is necessary to identify in precise. However, when the transceiver is set within the cage, the information of the emission wavelength is unable to distinguish even such information is recorded in the label stuck in the top and side surfaces of the transceiver. In the configuration that the emission wavelength is identified by the color code marked in the bridge portion of the bail, the information may be easily distinguished.

The base of the present invention, in the bottom thereof, may include a rib extending along a longitudinal direction and hollowed inward. On the other hand, the cover inevitably includes a slit extending along the longitudinal direction because the cover is made from a metal plate. In the present invention, a pair of edges forming the slit is each set within the rib. Therefore, the strength of the base and the cover may be enhanced by the rib and the edge within the rib, respectively.

The base according to the present invention may have a finger in the front end thereof to hold and to push the optical subassembly. The tip shape of the front finger of the base may trace the outer shape of the optical subassembly. The front finger may be divided into a plurality of fingers each bent from the primary surface of the base to form a gap. A shield block may be inserted into the gap. Moreover, an envelop curve of the tip of the bent fingers may trace the outer shape of the optical subassembly.

The optical transceiver may further include a shield plate, which is also made of metal, assembled with the optical subassembly. The shield plate comes in electrically contact with the base and the tab plate to shield the optical transceiver effectively.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A illustrates the outside appearance of the pluggable transceiver of the present invention, and FIG. 1B illustrates the transceiver set within in the cage;

FIG. 2 is an exploded view of the transceiver according to an embodiment of the present invention;

FIG. 3A illustrates the receptacle member and the tab plate to be attached with the receptacle member, and FIG. 3B illustrates the receptacle member assembled with the tab plate;

FIG. 4A illustrates a process for assembling the optical subassemblies with the receptacle member, and FIG. 4B illustrates the optical subassembly installed on the assembly of the receptacle member with the tab plate to form the OSA unit;

FIG. 5A shows the configuration of the base, and FIG. 5B illustrates the primary substrate, the supplementary substrate, and the insulating film inserted between the heat conducting plate and the supplementary substrates when the supplementary substrate is assembled on the heat conducting plate;

FIG. 6A is a downward view of the primary substrate temporarily assembled with the OSA unit and the base, and FIG. 6B shows a process for assembling the base with the primary substrate and the OSA unit;

FIG. 7A illustrates a process for assembling the heat conducting plate with the base and the primary substrate, and FIG. 7B illustrates the heat conducting plate partially assembled with the base;

FIG. 8A illustrates the OSA unit, the base, the primary substrate, and the heat conducting plate assembled with each other, and FIG. 8B illustrates the assembly where the supplementary substrate is set on the heat conducting plate;

FIG. 9A is a downward view of the heat conducting plate, while FIG. 9B is an upward view thereof;

FIG. 10A illustrated a modified heat conducting plate to be assembled with the modified base, and FIG. 10B illustrates the assembly of the modified heat conducting plate together with the modified base;

FIG. 11A illustrates the process for assembling the supporting plate with the heat conducting plate, FIG. 11B illustrates the body unit with the supporting plate assembled with the heat conducting plate, and FIG. 11C illustrates the supporting plate;

FIG. 12A illustrates the transceiver assembled with the actuator, FIGS. 12B and 12C are upward and downward views of the actuator, respectively, and FIG. 12D illustrates a portion of the receptacle member to be engaged with the actuator;

FIG. 13A illustrates the assembly of the receptacle member, the actuator, and the bail, and FIG. 13B shows the bail slightly rotated from the initial position;

FIG. 14A illustrates the body unit and the cover to be set thereto, and FIG. 14B is a cross section of the cover taken along the line A-A in FIG. 14A;

FIG. 15A illustrates the ground fin provided in the tip of the tab plate and that of the upper front of the cover, and FIG. 15B illustrates the bottom front of the cover;

FIG. 16 is plan views of the transmitter optical subassembly (TOSA) and the receiver optical subassembly (ROSA), each installed within the optical transceiver according to the present invention;

FIG. 17A shows a front end portion of the base according to embodiments of the present invention, and FIG. 17B is a front view of the base, where two OSAs are virtually shown by their outer diameter;

FIG. 18A shows a process for assembling a shield block between front fingers of the base, and FIG. 18B shows the shield block set between the front fingers of the base;

FIGS. 19A and 19B shows shield plate according to an embodiment of the present invention; and

FIG. 20A is a perspective view showing a process for setting the shield plate within the second necked portion of the OSA, and FIG. 20B is a plan view showing the shield plate, the necked portion of the OSA, and the receptacle member assembled with the tab plate, the OSA, and the shield plate.

DESCRIPTION OF PREFERRED EMBODIMENTS

Next, a configuration of an optical transceiver and a method for assembling the transceiver according to the present invention will be described as referring to accompanying drawings. FIG. 2 is an exploded view of the optical transceiver of the present invention. The pluggable transceiver 1 shown in FIG. 2 comprises a body unit and an optical subassembly unit. The body unit includes a primary substrate 17, a supplementary substrate 18, a supporting mechanism of these substrates, and a cover 23. The supporting mechanism comprises a base 20, a heat-conducting plate 21 and a supporting plate 22. The optical sub-assembly (OSA) unit includes transmitting and receiving optical subassemblies, 15 and 16, respectively, and members, 11 to 14, to show the optical coupling function as described below.

(OSA Unit)

The OSA unit includes, in addition to two optical subassemblies, 15 and 16, a receptacle member 13 made of resin, an actuator 12, a bail 11 and a tab plate 14. The bail 11 may be made of resin or metal. The bail 11 and the actuator 12 perform a mechanism to disengage the transceiver 1 from the cage 2. As described later in this specification, to rotate the bail 11, with a projection formed in both sides of the receptacle member 13 as the center of the rotation, moves the front end of the actuator 12 downward. The actuator 12 is fixed to the receptacle member 13 in the center thereof. Accordingly, due to the seesaw motion as this fixed point being the center of the rotation, the rear end of the actuator 12 is lifted upward, which pulls the projection formed in the tip of the rear end of the actuator 12 inward to release the engagement of the projection with the opening of the cage 2.

As for the releasing mechanism by the combination of the bail 11 and the actuator 12, it is known that the actuator 12 is slid backward as the rotation of the bail 11. In such mechanism, the projection to be engaged with the cage is fixedly formed in the bottom of the receptacle member 13 not the tip of the actuator 12. Inserting the transceiver 1 into the cage 2, the projection in the bottom of the transceiver engages with the opening of the cage 2 as deforming the cage 2. When releasing the transceiver 1 from the cage 2, the rear end of the actuator 12 spreads the cage 2 outward as sliding the actuator forward, thus disengaging the projection from the opening of the cage 2.

In both mechanisms, the rotation of the bail 11 releases the engagement of the transceiver 1 with the cage 2. In other words, it is not restricted to those mechanisms mentioned above as long as the transceiver provides a mechanism to release from the cage 2 and the rotation of the bail 11 originally causes this mechanism.

FIG. 16 shows an example of the TOSA 15 and the ROSA 16. Both subassemblies provide a CAN package that includes a stem, 15 a or 16 a, a plural lead pins, 15 b or 16 b, protruding from the stem, a cap, 15 g or 16 g, and a sleeve, 15 d or 16 d. A semiconductor optical device is installed within a space formed by the stem, 15 a or 15 b, co-operating with the cap, 15 g or 16 g, respectively. Between the sleeve, 15 d or 16 d, and the cap, 15 g or 16 g, is provided with a plurality of flanges, 15 c or 16 c, and between the flanges are formed with two necked portions, 15 e or 16 e, and 15 f or 16 f, respectively. As explained later, by setting the necked portion, 15 e or 16 e, to the receptacle member 13, the OSA may be positioned in the receptacle member. Moreover, the other necked portion, 15 f or 16 f, receives the shield plate 40.

An assembly of the receptacle member 13, the tab plate 14 and subassemblies, the TOSA 15 (Transmitting Optical Sub-Assembly) and the ROSA 16 (Receiving Optical Sub-Assembly), installed in the receptacle member 13, is called as an OSA unit 6 as a whole. From FIG. 3A to FIG. 4B show the process to assemble of the OSA unit 6. These figures are those viewed from the bottom side of the transceiver.

The OSAs includes the TOSA 15 and the ROSA 16 when the transceiver 1 has a function of the full-duplex communication standard. Both OSAs, 15 and 16, has a coaxial package. The ROSA 16 installs a semiconductor light-receiving device, which is typically an avalanche photodiode, APD, or a PIN-PD, collectively called as the PD, and a preamplifier for amplifying an electrical signal generated by the PD. On the other hand, the TOSA 15 installs a laser diode (LD) and, in addition to the LD, a PD for monitoring the optical output from the LD. A thermo-electric device, called as a Peltier device, may be also installed within the TOSA 15. Moreover, when the driving frequency of the LD exceeds 10 GHz, the driver for the LD may be also installed within the TOSA 15. The signals and power lines from the OSA to the substrate 17, or from the substrate 17 to the OSA, are transferred through lead pins, 15 b and 16 b, provided in the rear end of the OSA, which is so-called the stem, 15 a and 16 a. A flexible printed circuit (FPC) board may be used in place of the lead pins, 15 b and 16 b.

The receptacle member 13, which is made of resin, includes first to third portions, 13 a to 13 c, as shown in FIG. 3A. The first portion 13 a, positioned in the front end of the receptacle member 13, provides two cavity, 10 a and 10 b, into which the optical connector is to be inserted. These cavities are called as the optical receptacle. The outer side of the first portion 13 a forms a projection 13 d that becomes an axis of the rotation of the bail 11. The bottom of the first portion 13 a forms a projection 13 e in the center and two beaked hooks 13 f in both sides of the projection 13 e. These structures are arranged along the boundary to the second portion 13 b, as shown in FIG. 3A that look downs the bottom of the receptacle member 13. The center projection 13 e mates with the hollow formed in the center of the actuator 12 and two beaked hooks receives the axis 12 g, which enables the actuator 12 to operate in the seesaw motion around the axis 12 g.

The second portion 13 b includes side walls and a center partition 13 i, which forms two cavities 13 k to receive the TOSA 15 and the ROSA 16, respectively. The bottom of the cavity 13 k is opened in order to set the OSA therein. U-shaped cuttings are formed in the boundary wall 13 q to the third portion 13 c. The U-shaped cutting provides a groove 13 j along the exposed section, which receives one of the flange, 15 c or 16 c, of the OSA to position the OSA in the cavity 13 k. Thus, setting the OSA within in the cavity 13 k, the sleeve, 15 d or 16 d, formed in the head portion of the OSA, protrudes into the optical receptacles, 10 a and 10 b, of the first portion 13 a. Accordingly, the semiconductor optical device such as LD or PD installed within the OSA may optically couple with the optical fiber in the optical receptacles, 10 a and 10 b. The optical fiber provides, in the tip thereof, the optical connector to be inserted into the receptacle. Since the physical dimensions of the optical receptacles, 10 a and 10 b, and the position of the sleeves, 15 d and 16 d, with respect to the optical receptacles, 10 a and 10 b, are precisely ruled, the position of the OSA, 15 and 16, in particular the sleeve thereof, must be positioned with respect to the receptacle member 13.

In a center of the side wall 13 h forms a projection 13 g. As described later in this specification, to mate this projection 13 g with an opening in the tab plate 14 and an opening in the cover 23 assembles the tab plate 14 and the cover 23 with the receptacle member 13. The projection 13 g has a gentle slope in a side where the tab plate 14 is inserted to mate the projection 13 g smoothly with the tab plate 14, while, another side thereof has a steep slope in order to prevent the tab plate 14 and the cover 23 once engaged with the projection 13 g from easily releasing.

The third portion 13 c includes an upper wall 131 continued from the upper wall in the second portion 13 b and two projections formed in both ends thereof to mate with the base 20.

The tab plate 14 includes first and second portions, 14 a and 14 b. The first portion 14 a forms a plurality of fins, 14 c, 14 d and 14 f, which surround the receptacle member 13 and extend outward. These fins, 14 c, 14 d and 14 f, as described later, are to come in contact to the inside of the cage 2 to function the electromagnetic interference (EMI) shield. The fin 14 d in both sides and another fin 14 f in the bottom have a shape that the center portion 14 thereof protrudes to come in contact reliably to the inside of the cage 2. The tip of the fins, 14 c, 14 d and 14 f, configures in wavy and the bottom portion of this wave fits within the groove formed between the first 13 a and second 13 b portions of the receptacle member 13. The fin 14 d in both sides has an opening 14 e within which a latch tab 14 e is formed. A center hole of this latch tab 14 e engages with the projection 13 g of the receptacle member 13 to assemble the tab plate 14 with the member 13.

The second portion 14 b of the tab plate 14 is folded twice. That is, to bend a surface 14 g extending form the fin 14 f in almost right angle forms a surface 14 h, and to bend again in almost a right angle forms another surface 14 i. The surfaces, 14 g and 14 i, put the upper wall 131 of the receptacle member 13 therebetween. Thus, the tab plate 14 is securely assembled with the receptacle member 13.

The second portion 14 b, bent in almost right angle to a direction opposite to the fin 14 f, forms a surface 141. This surface 141 provides two cuttings tracing the U-shaped cutting of the receptacle member 13. In the deep end of this cutting provides a latch tab 14 k that fits to the groove 13 n formed in the bottom of the U-shaped cutting of the receptacle member 13 to position the tab plate 14 with respect to the receptacle member 13. A center of this surface 141, between two U-shaped cuttings, forms a spacer 14 j by bending the tab plate 14. The width of the U-shaped cutting of the surface 141 is set slightly smaller than the diameter of the OSA. Accordingly, the OSA once set within the cutting of the tab plate 14, is hard to disassemble. The tip of this spacer is curved inward to form a socket 14 n, into which the center post 20 f of the base 20 is inserted to build the base with the receptacle member 13. Moreover, a portion in the receptacle member 13 facing this spacer 14 j forms a plateau 13 r, against which the tip of the center post 20 f of the base 20 is abutted. The tab plate 14 is made from a metal plate with a thickness of about 0.15 mm and may be made of stainless steel only by cutting, bending and tapping without welding, gluing, or screwing, which may not only reduce the cost but also decrease the manufacturing cost.

FIG. 3B shows the assembly of the receptacle member 13 with the tab plate 14, FIG. 4A shows a process for setting the OSA into this assembly of the receptacle member 13 with the tab plate 14, and FIG. 4B shows that the OSAs, 15 and 16, are set within the cavities 13 k of the receptacle member 13 with the flanges, 15 c and 16 c, aligned within the U-shaped cutting. Setting the OSA, 15 and 16, within the receptacle member 13 together with the tab plate 14, a respective pairs of the flanges, 15 c and 16 c, of the OSA put the wall 13 q behind the groove 13 j forming the U-shaped cutting therebetween together with the surface 141 of the tab plate 14. Using the metal sleeve, 15 d and 16 d, and providing the latch tab 14 k in the deep end of the U-shaped cutting of the tab plate 14, the electrical conduction from the tab plate 14 to the metal sleeves, 15 d and 16 d, may be ensured. Since the tab plate 14 is connected to the cage 2 by the fins thereof, 14 c, 14 d, and 14 f, the present transceiver 1 may firmly and securely ground the metal sleeves, 15 d and 16 d.

(Body Unit)

Next, the body unit of the transceiver 1 will be described. The body unit includes the base 20, the cover 23, the primary substrate 17, a supplementary substrate 1, the heat-conduction plate 21, and the supporting plate 22.

FIGS. 5A and 5B show the primary and supplementary substrates, 17 and 18, and the base 20. On the primary substrate 17 is installed with an electronic circuit including an integrated circuit (IC) 17 c. A laser driver for driving the LD, a signal processor for extracting a clock component and a data component from an amplified signal sent from the ROSA 16, or, when the APD is used as a light-receiving circuit, a bias controller for generating and adjusting the reverse bias voltage provided to the APD, are known as the electronic circuit installed on the substrates, 17 and 18. Moreover, when the thermo-electric controller such as the Peltier device is installed within the TOSA 15, the Peltier driver is also installed within the substrates, 17 and 18. When the size of the circuit above mentioned becomes large, or an additional circuit such as a processor for controlling in inclusive those circuits and a memory are necessary to be installed within the transceiver 1, the supplementary substrate 18 may install circuits not processing a high speed signal, typically the controlling circuit for the APD and the Peltier driver.

The primary substrate 17 connects to the supplementary substrate 18 with a FPC board 18 d. This FPC board 18 d is soldered to the primary substrate 17 extending from the side of the supplementary substrate 18. As described later, the supplementary substrate 18 is overlaid on the primary substrate 17 by folding this FPC board 18 d. The insulating film 19 is inserted between the supplementary substrate 18 and the heat conducting plate 21 to prevent the back side of the supplementary substrate 18 from electrically shorting to the heat conducting plate 21.

On the rear end of the primary substrate 17 is provided with an electrical plug 17 f. This plug 17 f may mate with the electrical connector in the deep end of the cage 2, which enables the electrical communication of the electrical circuit installed within the transceiver 1 with that of the host system. To configure the electrode of this plug 17 f with the predetermined pattern may realize the hot-pluggable function where the transceiver 1 may insert into or remove from the cage as the host system is powered on.

The electrical connection between the circuit installed on the primary substrate 17 with the OSAs, 15 and 16, are performed by lead pins, 15 b and 16 b. The primary substrate 17 provides electrodes, 17 a and 17 b, each electrically connected to the lead pins, 15 b and 16 b, of the OSA. The FPC board may serve as the lead pins. When the operational speed of the transceiver 1 enters the zone over 1 GHz, it is preferable to connect the OSAs, 15 and 16, to the primary substrate 17 with a means that secures the impedance-matching condition. Even the FPC board connects the OSAs, 15 and 16, to the primary substrate 17; the interconnection formed on the FPC board may be a micro-strip line or a co-planar line with the impedance-matched configuration. Moreover, when the electrical connection is carried out under an impedance-mismatched condition, it is preferable to make the coupling means as short as possible to suppress the deterioration in the signal transferred from/to the OSAs, 15 and 16 by the impedance mismatching.

The primary substrate 17 forms a plurality of notches 17 e in the side thereof. As described later, to fit this notch 17 e to the projection 20 k formed in the base 20 and to abut the step 17 d formed in the rear side of the substrate 17 against the side wall of the coupling portion 20 h automatically determines the longitudinal position of the substrate 17 within the transceiver 1.

The base 20 covers the bottom side of the OSA and mounts the primary substrate 17 thereon. The base 20 is also made from a metal plate, such as iron or stainless steel, by cutting, bending and tapping without gluing, welding and screwing, which reduces the cost of the transceiver 1. That is, the base 20 includes a first portion 20 a and a second portion 20 b. The first portion 20 a provides a space opened upward to install the primary substrate 17 thereon. The second portion 20 b, formed in the rear of the first portion 20 a, provides a space opened downward to install the heat-conducting plate 21.

The first portion 20 a includes a bottom 20 g, a pair of sides 20 c extending from the bottom 20 g, a support 20 d that constitutes a portion of the sides 20 c, and a front wall 20 ne extending from the bottom 20 g at the front edge. On the center of the bottom 20 g is formed with a rib 20 q extending along the longitudinal direction of the transceiver 1 and depressed inward. The front end of the bottom 20 g forms a center post 20 f that is, as aforementioned, inserted into the socket 14 n of the tab plate 14, and abutted in the tip thereof against the plateau 13 r to assemble the base 20 with the receptacle member 13 and the tab plate 14. The rib 20 q not only positions the cover 23 when the base 20 is put into the cover 23 but also mechanically strengthens the base 20.

The bottom 20 g further forms two openings 201, through which the soldering between the lead pins, 15 b and 16 b, of the OSA to the primary substrate 17 may be carried out. The substrate 17 is a double-sided wiring substrate to enhance the flexibility of the interconnection. Although FIG. 5B illustrates electrodes, 17 a and 17 b, only on the front surface of the substrate 17, electrodes similar to that of the front side are formed in the back side, and the lead pins, 15 b and 16 b, sandwiches the substrate 17 to connect the lead pins to the electrodes in both sides thereof. Since to set the substrate 17 to the base 20 hides the electrodes in the back side, the openings 201 exposes the electrodes and the lead pins in the back side to enable the soldering.

The side for the TOSA in the bottom 20 g places the thermal sheet 27 thereon in advance to the assembly. The thermal sheet 27 comes in contact to the stem 15 a of the TOSA 15 to dissipate heat generated within the TOSA 15 to the cover 23 via the base 20. Although the ROSA 16 generates heat greater than that from the TOSA 15 because the ROSA installs the pre-amplifier in addition to the PD, such circuit generally shows the dull temperature dependence compared to that of the LD. The LD shows the strong temperature dependence in its light-emitting characteristic. Therefore, the thermal sheet 27 is provided only for the TOSA 13. When the preamplifier installed within the ROSA 16 generates larger heat, for example, in the operational speed greater than 10 GHz, it is preferable to provide the thermal sheet for the ROSA 16.

The side 20 c forms a projection 20 k in a center thereof and two steps 20 m putting the projection 20 k therebetween. The projection 20 k, as previously described fits into the notch 17 e formed in the side of the substrate 17 to position the substrate 17. The step 20 m stabilizes the substrate 17 by overlaying the substrate 17 thereon. Without the step 20 m, the substrate 17 comes in contact to the base 20 only by the section of the side 20 c, which may be unstable for the substrate 17. The step 20 m, which is formed by bending a portion of the side 20 c inward, secures the stability of the substrate 17 with respect to the base 20.

The front portion of the side 20 c forms the support 20 d continuously extending upward. The support 20 d provides the opening 20 e in a center thereof that engages with the projection 13 m of the receptacle member 13 to assemble the base 20 with the receptacle member 13. The front wall 20 n configures a gentle U-shape that follows the outer shape of the OSAs, 15 and 16.

FIGS. 17A and 17B show a detail of the front end of the base 20. One embodiment of the front wall 20 n is shown right hand side of FIG. 17B, where the shape of the front wall 20 n traces the outer peripheral of the necked portion, 15 e or 16 e, of the OSA. The other example is also shown in FIG. 17, where the front wall of the base 20 is divided into three fingers, 20 t to 20 v, two of which extend forward compared to the rest finger. In the example shown in FIG. 17, both side fingers, 20 t and 20 u, protrude compared to the center finger 20 v. Moreover, an envelop curve of the tip shape of these fingers traces the diameter D of the necked portions, 15 e or 16 e, of the OSA as shown in FIG. 17B, which enables to hold the OSA stably. In one modification, the envelope curve of the tip shape may be slightly larger than the diameter D of the necked portion, 15 e or 16 e, by taking a tolerance a of the diameter D.

To hold the OSA with three fingers whose positions along the longitudinal direction are different from each other gives an equivalent mechanism that the OSA is held by a finger whose thickness is the same with the gap between fingers. Thus, this type of the front fingers may give a steady pressure to the OSA.

In the example shown in FIG. 17, the center finger 20 v positions behind the side fingers, 20 t and 20 u. However, a positional relation between fingers is not restricted to those shown in FIGS. 17A and 17B. The side fingers, 20 t and 20 u, may position behind the center finger 20 v. A function appeared in FIG. 17 may be accomplished by arrangements where one of fingers positions behind the others. Two fingers whose positions are different from each other may be also applicable.

In summary, one embodiment of the present invention provides a plurality of fingers in the front end of the base 20. Some of fingers are bent at a first position, while the rest of fingers are bent at a second position different from the first position along the longitudinal direction of the base 20. These fingers in the tip end thereof trace the outer shape of the necked portion of the OSA and hold the OSA reliably. These fingers correspond to a holding portion of the base 20.

When the sleeve, 15 d or 16 d, or the components for the optical alignment are made of metal, the YAG laser welding may be a preferable means to fix the components permanently. However, the YAG laser welding is unable for the resin made component or sleeve. An adhesive is only technique to fix such resin made components. The present arrangement of the holding portion of the base 20 may show the preferable function to press the necked portion, 15 e or 16 e, of the OSA even if the necked portion or the sleeve, 15 d or 16 d, is made of resin and fixed by the adhesive.

FIG. 18 shows a variation of the arrangement shown in FIG. 17. This variation provides a shield block 30 made of electrically conducting material and put between the fingers, 20 t to 20 v. The arrangement that is shown in FIG. 18 without the shield block 30 causes a gap between the fingers. Moreover, depending on the envelope curve and its traceability for the outer shape of the necked portion, 15 e or 16 e, another gap may be occasionally formed between the base 20 and the OSA. Such gaps may degrade the EMI tolerance.

In the variation shown in FIG. 18, the shield block 30 is set between the fingers, 20 t to 20 v. Moreover, a surface of the shield block 30 that faces and comes in contact to the necked portion, 15 e or 16 e, also has a shape to trace the outer shape of the necked portion. Thus, this arrangement enhances not only the holding capability of the base 20 for the OSA but also the EMI shielding of the transceiver 1.

The shield block 30 has a simple outer shape, which does not restrict a material to be applied. An electrically conductive resin sheet, a radiation absorber, and a metal formed by, for instance, the extruding, the sheeting, the casting or the forging are usable.

The rear portion of the side 20 c forms the coupling portion 20 h by extending upward. The second portion 20 b includes a coupling surface 20 i by bending this coupling portion 20 h inward. The coupling surface 20 i includes a pair of tabs 20 j by bending a portion thereof downward, to be put between the legs 21 k of the heat-conducting plate 21. The rear end of the coupling surface 20 i is partially bent downward to form the surface 20 r and to protrude the rest portion 20 s rearward. As described later, the gap d₁ between the coupling surface 20 i is set slightly narrower than the width of the spacer tab 211. Assembling the heat conducting plate 21 with the base 20, the coupling surface 20 i of the base 20 is to be spread outward by the spacer tab 211, while the legs 21 k of the heat conducting plate 21 presses the tabs 20 j inward, which fits the heat conducting plate 21 to the base 20. The front and rear ends of the coupling surface 20 i is bent downward to form surfaces, 20 p and 20 r, to abut against the heat-conducting plate 21, which perform the similar function to that between the tab 20 j and the leg 21 k. The second portion 21 b of the heat conducting plate 21 assembles with the base 20 by fitting the surfaces, 20 p and 20 r, in the base 20 between the surfaces, 21 i and 21 s, and by fitting the tabs 20 j between the legs 21 k.

Thus, the base 20 of the present invention is made from a metal plate with cutting, bending, and tapping without welding, gluing, screwing or casting. The rib 20 q in the bottom secures the mechanical strength of the base 20. Moreover, the assembly with the substrate 17, the receptacle member 13 and the heat conducting plate 21 may be carried out only by fitting, which not only reduces the material cost but also simplifies the assembling process.

Next, the heat-dissipating mechanism of the transceiver 1 will be described. It is inevitable to consume greater power by the devices used in the transceiver 1 as the operational speed thereof increases. Therefore, the heat-dissipating mechanism for these devices becomes necessary. However, since the pluggable transceiver 1 is used by inserting into/extracting from the cage 2, it is impossible to provide a mechanism such as the heat-dissipating fin, although quite popular in the electronic equipment, in the outer surface of the transceiver. These fins prevent the transceiver 1 from smoothly inserting into/extracting from the cage 2. Due to the same reason, it is prohibited that the outside of the transceiver 1 comes in contact to the inside of the cage 2.

The heat conducting plate 21 primarily performs the heat-dissipating mechanism of the present transceiver 1. From FIG. 7A to FIG. 8B illustrate the heat-conducting plate 21 to be assembled with the base 17, while FIGS. 9A and 9B illustrate the configuration of the heat-conducting plate 21 from the top (FIG. 9A) and from the bottom (FIG. 9B). The heat-conducting plate 21 is also made from a metal plate only by cutting and bending. The plate 21 includes first to fourth portions, 21 a to 21 d. The first portion 21 a configures a substantially rectangle surface 21 g, connected to the third portion 21 c by bending a rear end thereof upward. This third portion 21 c connects the second portion 21 b by bending the other edge. The second portion 21 b becomes substantially in parallel to the first portion 21 a and covers a portion of the first portion 21 a. The fourth portion 21 d is bent by the other end of the second portion 21 b downward to form a surface 21 i.

The first portion 21 a includes a surface 21 g with a substantially rectangular, back surfaces, 21 e and 21 f. A plurality of legs 21 j extends from a pair of sides thereof downward by bending, tips of which come in contact to the primary substrate 17 to press down the substrate 17. A pair of support posts 21 m extends upward from the same sides, from which the legs 21 j extends downward. The tips of the support are bent to form the abutting surface 21 n. The back surface 21 e of the first portion 21 a comes in contact to the whole upper surface of the IC 17 c installed on the substrate 17 to conduct heat from the IC 17 c to the heat-conducting plate 21. The heat conducted to the plate 21 is transferred in the first portion 21 a rearward through other surface 21 f of the first portion 21 a to the third portion 21 c. It is preferable to put the thermal sheet 24 between the IC 17 c and the back surface 21 e of the plate 21 to enhance the efficiency of the heat conduction. The length of the leg 21 j is determined to take the thickness of this thermal sheet 24 and that of the IC 17 c into consideration. It is preferable to set the length of the leg 21 j slightly smaller than the total thickness of the IC 17 c and the sheet 24. To press this abutting surface 21 n downward by setting the cover 23 ensures the thermal contact between the plate 21 and the sheet 24 and between the sheet 24 and the IC 17 c.

The third portion 21 c extrudes rearward to come the end surface 21 h in contact to the inner end of the cage 2, which enhances the heat transferred to the plate 21 from the IC 17 c to dissipate to the cage 2. Even the end surface 21 h comes in contact to the cage 2, the insertion into/extraction from the cage 2 of the transceiver 1 is not affected at all. Only the rear end surface 21 h of the transceiver 1 provides the effective heat-dissipation path to the cage 2. The present transceiver 1 enables to dissipate heat generated from the IC 17 c installed in the middle thereof to the cage 2 by the heat conducting plate 21. The performance of the heat conduction of the plate 21 depends on the cross section thereof. Since the width of the plate 21 is inherently restricted by the width of the transceiver 1, the performance of the heat dissipation primarily depends on the thickness of the plate 21. The present transceiver 1 uses copper based alloy with a thickness of 0.5 mm, which shows a quite effective heat-dissipating function.

The second portion 21 b overlaps a rear half of the surface 21 of the first portion 21 a. The second portion 21 b also configures a substantially rectangular, an upper surface 21 r thereof coming in contact with the inside of the cover 23 to assist the heat-dissipation from the plate 21 to the cover 23. Both sides of the second portion 21 b have tabs 21 k by bending downward to put the tab 20 j formed in coupling surface 20 i of the base 20 therebetween. Moreover, the rear of the second portion 21 b is bent downward to form the spacer tab 211. The width of this spacer tab 211 is set to be slightly wider than the gap d₁ between the coupling surfaces 20 i of the base 20. Assembling the heat conducting plate 21 with the base 20, the spacer tab 211 and the tab 21 k transversely put the coupling surface 20 i therebetween, while the surfaces, 21 i and 21 s, longitudinally put the coupling surface 20 i therebetween. Thus, the heat-conducting plate 21 is assembled with the base 20 only by fitting the coupling surface 20 i of the base 20 into the second portion 21 b of the plate 21 without any screw, welding, or gluing, which enables to simplify the assembling process of the transceiver 1.

The area of the first portion 21 a not overlaid by the second portion 21 b mounts the supplementary substrate 18 as described later. One side of the first portion 21 a is cut to pass the FPC board connecting the supplementary substrate 18 to the primary substrate 17.

FIGS. 10A and 10B illustrate one modification of the base 20 and the heat conducting plate 21 shown in FIG. 5 and FIG. 9, respectively. The base 200 illustrated in FIG. 10A is configured in the coupling surface 200 i to be wider than the surface 20 i in the base 20 of FIG. 5A. The side cross section of the heat conducting plate 210 has a zigzag shape not the U-shaped configuration of the heat conducting plate 21. That is, the heat conducting plate 210 of this embodiment includes the first portion 210 a coming in contact to the IC 17 c, the fourth portion 210 d bent upward at the rear end of the first portion 210 a, the second portion 210 b bent at the upper end of the fourth portion 210 d, and the third portion bent downward at the rear end of the second portion 210 b. The heat generated in the IC 17 c is conducted to the first portion 210 a via the thermal sheet 24, transferred in the heat conducting plate 210, and finally dissipated to the cage 2 at the rear end surface 210 h of the third portion 210 c.

Moreover, the third and fourth portions, 210 c and 210 d, configure to extend downward from the second portion 210 b so as to put the coupling surface 200 i therebetween. The whole coupling surface 200 i of the base 200 comes in contact to the back surface of the second portion 210 b. The first portion 210 a forms legs 210 j extending downward while supports 210 m extending upward from the sides thereof. The tip of the support 210 m becomes the abutting surface 210 n to come in contact to the inside of the cover 23. The difference between two embodiments is that the present heat conducting plate 210 presupposes not to install the supplementary substrate 18. Although the first portion 210 a has a space opened upward similar to the previous embodiment, this is for the direct contact of the heat conducting plate 210 to the IC 17 c not to install the supplementary substrate 18.

Standards similar to those appeared in the previous embodiment may be applied for the selection of the material and its thickness for the heat conducting plate 210 of this embodiment. Further, the heat conducting plate 210 is also made from a metal plate only by cutting and bending without any welding and gluing. The plate 210 of this embodiment does not provide an overlaid portion, corresponding to the portion 21 f in the previous embodiment, of the first portion 210 a and the second portion 210 b. Accordingly, the plate 210 may save the metal plate. The heat dissipating mechanism of this embodiment has the same efficiency with those in the previous embodiment.

FIGS. 11A and 11B illustrate that, after installing the supplementary substrate 18 onto the first portion 21 a of the heat conducting plate 21, the supporting plate 22 is set to hold the supplementary substrate 18. As shown in FIG. 5B, the FPC board 18 d connects the supplementary substrate 18 to the edge of the primary substrate 17. Installing the primary substrate 17 on the first portion 20 a of the base 20, and setting the heat conducting plate 21 on the primary substrate 17, the supplementary substrate 18 is set on the first portion 21 a of the heat conducting plate 21 so as to fold the FPC board 18 d. At that time, the support post 21 m of the heat conducting plate 21 passes through the opening 18 e in the supplementary substrate 18. The rear end 18 a of the supplementary substrate is configured to protrude from the primary portion thereof, as shown in FIG. 5B, which fits into the cutting portion 21 q of the heat conducting plate 21. Since the supplementary substrate 18 is not fixed to the plate 21, the supporting plate 22 assists to fix the supplementary substrate 18 to the plate 21. Moreover, the side of the FPC board 18 d forms a projection 18 g. This projection is inserted behind the coupling portion 20 h at the assembling of the supplementary substrate 18 onto the heat conducting plate 21. Accordingly, this projection may prevent the cover 23 from scratching the edge of the FPC board 18 d when setting the cover 23 to the body unit.

The supporting plate 22, as shown in FIG. 1C, is also made from a metal plate by cutting, bending, and tapping, and includes first to fourth portions, 22 a to 22 d. The first portion 22 a forms an opening 22 f and a step. The opening 22 f softens the resilient force of the tip portion 22 j that comes in contact to the back surface 21 r of the heat conducting plate 21. The legs 221 in the first portion 22 a form a step 22 g by cutting a portion of the tip thereof, which inserts into the notch portion 18 f of the supplementary board 18. Moreover, the tabs 22 i of the second portion 22 b comes in contact to the side of the support post 21 m of the heat conducting plate 21, and the legs 22 e in the fourth portion 22 d also forms a step 22 m by cutting a portion of the tip thereof, which inserts into the cutting portion 18 g formed in both front sides of the supplementary substrate 18. That is, the supporting plate 22 is assembled with the supplementary substrate 18 and the heat conducting plate 21 by three points, the steps, 22 g and 22 m, in the legs of the supporting plate and the tab 22 i.

The third potion 22 c that connects the second portion 22 b to the fourth portion 22 d configures in a beam to be bent outward by about 0.2 mm, which shows a resilient force. Putting the cover 23, the cover 23 in the center thereof comes in contact to and presses down this beam. Consequently, the fourth portion 22 d of the supporting plate 22 is pressed downward to fix, by the tip 22 m thereof, the supplementary substrate 18 to the heat conducting plate 21.

FIG. 12A illustrates the transceiver 1 including the OSA unit 6, the base 20, the primary and supplementary substrates, 17 and 18, the heat conducting plate 21 and the supporting plate 22, and completes the assembling thereof. The transceiver 1 shown in FIG. 12A further includes the actuator 12 in the front end thereof. Next, the actuator 12 and the configuration of the front side of the receptacle member 13 where the actuator 12 is assembled will be described as referring to FIGS. 12B to 12D.

FIG. 12B illustrates the actuator 12 from the bottom, while FIG. 12C shows the configuration of the upper surface of the actuator 12. The actuator 12 includes first to third portions, 12 a to 12 c, and is capable of rotating around the axis 12 g formed in the third portion 12 c, which makes a seesaw motion for the first and second portions, 12 a and 12 b, provided in both sides of the third portion 12 c. The front end of the first portion 12 a forms a pressing surface 12 d, while both sides thereof configures inner and outer sliding surfaces, 12 i and 12 h, respectively. Rotating the bail 11, this rotational motion of the bail 11 may be converted to the up-and-down motion of the first portion 12 a because two surfaces, 11 f and 11 h, of the bail 11 put these inner and outer sliding surfaces, 12 h and 12 i. That is, two surfaces, 11 f and 11 h, of the bail function as a cam. The second portion 12 b provides an arm 12 f and a projection 12 e in the tip of this arm 12 f. The projection 12 e fixes the transceiver 1 to the cage 2 by engaging with the opening of the cage 2 and, by the seesaw motion of the actuator 12 due to the rotation of the bail 11, is brought inward to the transceiver 1, which enables to disengage the projection 12 e with the opening and to release the transceiver 1 from the cage 2.

FIG. 12D illustrates the front configuration of the receptacle member 13. Two openings, the optical receptacles, 10 a and 1 b, receives the optical connector, and the TOSA 15 and the ROSA 16 installed on the other side of the receptacle member 13 may optically couple with the optical fiber attached to the optical connector. On the bottom of the receptacle member 13, in the center thereof, is configured with a projection 13 e, whose section is semicircular, and, in both sides thereof, are configured with beaked hooks. On the other hand, the actuator 12 forms a hollow 12 j in the center of the upper surface thereof to receive the center projection 13 e of the receptacle member 13, and the axis 12 g is fitted into the beaked hook 13 f. The center projection 13 e restricts the movement of the actuator 12 in the longitudinal direction, while the beaked hook 13 f restricts the up-and-down motion thereof, accordingly, the actuator 12 may not be disassembled with the receptacle member 13. On the side walls of the receptacle member 13 are configured with the projection 13 d, which becomes the axis for the rotation of the bail 11, as a portion 13 p thereof is scooped.

FIG. 13A illustrates the bail 11 and the actuator 12, both assembled with the receptacle member 13, viewed from the front side, while FIG. 13B is a side view of these members. The bail 11 is a U-shaped member including a pair of legs 11 b and a bridge 11 a connecting these legs 11 b. Although the following description primarily concentrates on the bail 11 made of metal by cutting and bending, the bail 11 may be made of resin. A center of the leg 11 b forms an opening 11 c to receive the projection 13 d on the side wall of the receptacle member 13, a portion 11 d of the edge thereof extrudes into the opening 11 c and is set within the lacked portion 13 p of the projection 13 to restrict the rotation of the bail 11.

Setting the bail in the neutral position, the initial position, the openings, 10 a and 10 b, of the optical receptacle wholly exposes not to be hidden by the bail 11. As shown in FIG. 13A, the sliding surface 11 h and the cam surface 11 f of the bail 11 put and come into contact to the inner and outer sliding surfaces, 12 h and 12 i. Rotating the bail 11, this rotational motion of the bail 11 operates to the actuator 12. That is, until the angle of the rotation θ, the bail 11 makes no operation to the actuator 12. The angle θ is determined when the cam surface 11 f wholly comes in contact to the inner sliding surface 12 i, as shown in FIG. 13B.

Further rotating the bail 11, the cam surface 11 f presses down the inner sliding surface 12 i, which continues until the outer surface 11 i of the leg 11 b comes in contact to the inner sliding surface 12 i. Thus, by the first portion 12 a of the actuator 12 pressing downward, the projection 12 e in the second portion 12 b is drawn up by the seesaw motion of the actuator 12, which may disengage the projection 12 e with the opening of the cage 2.

During the rotation of the bail 11, the sliding surface 11 h of the bail 11 supports the outer sliding surface 12 h of the actuator 12, consequently, the actuator 12 is inevitably connected with the bail 11. In other words, the actuator 12 makes the seesaw motion as the inner and outer sliding surfaces, 12 h and 12 i, are put between the cam surface 11 f and the sliding surface 11 h of the bail 11. Moreover, the cover 23 supports the actuator 12 by the fin 23 d thereof extending from the front edge of the cover 23 (FIG. 14A). The projection 11 d within the opening 11 c of the leg 11 b slides only in the lacked portion 13 p of the projection 13 d. This combination of the projection 11 d and the lacked portion 13 p operates as the stopper for the rotation of the bail 11. When the bail 11 returns from the rotated position to the neutral position, the initial position in FIG. 13A, the operation mentioned above are performed in the opposite procedure.

In the description above, the bail 11 is rotated to disengage the transceiver 1 with the cage 2 by pulling the projection 12 e inward. However, when the host system densely installs a plurality of cages 2 and the transceivers neighbor to the target transceiver receive the optical connector attached with the optical cable, a situation may occur that the bail can not rotate because the optical cables of the neighbor transceivers prevent from touching the bridge portion 11 a of the bail 11. The transceiver of the present invention may exhibit the same function with the rotation of the bail 11 by pressing down the front end 12 d of the actuator 12.

As shown in FIG. 13 b, pressing the front end 12 d of the actuator 12 downward, the outer sliding surface 12 h pushes the sliding surface 11 h of the bail 11 rearward, which influences the rotational moment on the bail 11. The combination of the conventional bail and the actuator may not convert the force downward for the actuator 12 into the rotational moment of the bail 11. The force applied to the actuator 12 may not convert to the rotational moment of the bail 11 because the bail itself operates as the stopper, thereby being unable to release the transceiver 1 from the cage 2. The mechanism provided in the present invention converts the force applied to the front end of the actuator 12 is adequately converted to the rotational motion of the bail 11, which enables the transceiver 1 to be released from the cage 2.

Recently, the pluggable transceiver 1 is proposed to be applied in the wavelength division multiplexed (WDM) system. In the WDM system using the pluggable transceiver, which provides functions of the optical transmission and the optical reception, the emission wavelength of the optical transmission function is set to be a preset value, and a plurality of optical signals each having the preset wavelength is transmitted by being multiplexed in the outside of the transceiver. In this case, each transceiver is inevitable to have an inherent emission wavelength. However, as shown in FIGS. 1 and 2, even the label attached in the upper or the side of the body records the information of the emission wavelength, it is unable to discriminate the information when the transceiver 1 is set within the cage 2. Accordingly, the present transceiver proposes a configuration that the bridge portion 11 a of the bail 11 provides the colored identification, which enables to distinguish visually the emission wavelength even when the transceiver 1 is in the cage 2.

According to the WDM communication standard in the wavelength band of 1.5 μm, the optical signals are divided into 64 channels by the interval of 0.8 nm, which corresponds to 100 GHz in the frequency, and are multiplexed in the wavelength band from 1530 nm to 1650 nm. In order to distinguish respective wavelengths, the last two digits in the integer part and one digit after the decimal point, total three digits, may be marked in the color code. One example of color codes is shown in the following table:

TABLE Example of color code Number Color 0 Black 1 Brown 2 Red 3 Orange 4 Yellow 5 Green 6 Blue 7 Magenta 8 Gray 9 While

By spacing between the first two digits, which corresponds to the integer part, and the last one digit that corresponds to the one after the decimal points, the position of the decimal point maybe distinguished. Such colored codes can be recognized when the bail 11 is rotated in front of the optical receptacles, 10 a and 10 b, even when the transceiver 1 is in the cage 2. In stead of spacing between the digits, to mark the identification may be recognizable to denote the position of the decimal point and to distinguish the emission wavelength. Moreover, three digits for the integer part, the total of four digits, may be applicable for the identification.

The cover 23 is made from a metal plate with a thickness of about 0.3 mm by cutting and bending without any welding and gluing. The metal used for the cover 23 may be stainless, iron or copper alloy. The cover 23 is fit from the rear side of the transceiver 1 to cover the body unit thereof exposing only the optical receptacle 10. The bottom of the cover 23 forms a slit with two edges, 23 a and 23 b, forming this slit are fitted within the rib 20 q formed in the bottom 20 g of the base 20, as shown in FIG. 14B. This configuration of the slit and the rib 20 q strengthens the transceiver 1 against the stress despite the cover 23 is made from a metal plate by bending.

The cover 23 forms a large opening 23 e in the front bottom to protrude the projection 12 e of the actuator 12 to engage with the opening in the cage 2. The upper surface of the cover 23 forms a plurality of structures, as shown in FIG. 1A, which includes two slits parallel to each other and a portion between these two slits is bent inward. This bent portion has a resilient function and comes in contact to the second portion 21 b and to the abutting surface 21 n of the heat conducting plate 21 when the cover 23 is fit to the body unit. Consequently, the heat conducting plate 21 not only securely comes in contact to the IC 17 c but also ensures the heat dissipation path from the heat conducting plate 21 to the cover 23.

FIGS. 15A and 15B illustrate the front end of the transceiver 1 fitted with the cover 23. Fins, 14 d and 14 f, protrude from the front end of the cover 23. The upper of the transceiver 1 also forms the ground tab 23 g that surrounds the fin 14 f. In the midsection 14 m of the fin 14 f protrudes to securely come in contact to the inside of the cage 2. It may be applicable that this midsection 14 m projects outward by forming two slits parallel to each other and surrounding the mid section 14 m. That is, the fin 14 f may be the double fin with the sub-fin 14 m in the tip thereof. The double fin may have another slit connecting those two slits in the ends thereof. Moreover, another fin 14 d may form the midsection protruding from the peripheral thereof, and the double fin structure 14 m may be also applicable to this another fin 14 d.

By applying such configuration to the fins, 14 f and 14 d, the transceiver 1 may securely come in contact to the cage 2. The multiple contacts of the fins, 14 f and 14 d, the double fin structure 14 m, and the ground tab 23 g of the cover 23 makes the contact of the transceiver 1 to the cage 2 secure. Since the cage 2 is made from a metal plate, the shape thereof is easily deformed. Even when the transceiver 1 is formed in firm, the secure contact between the transceiver 1 and the cage 2 may be performed if the cage 2 is deformed. The multiple contact of the present invention ensures the secure contact therebetween.

FIG. 15B illustrates the bottom of the front end of the transceiver 1. The fin 23 d of the cover supports the actuator 12 and the projection 12 e protrudes from the opening 23 e. Moreover, the fin 14 c protrudes from both sides of the fin 23 d to set in the tip thereof within the groove at the boundary between the second and third portions, 13 b and 13 c, respectively, of the receptacle member 13. The side fin 14 d of the tab plate 14 is also set within the groove at the boundary between second and third portions, 13 b and 13 c.

Next, an assembling process of the present optical transceiver will be described in sequence.

1. Assembling of the Receptacle Member with the Tab Plate

First, as shown in FIG. 3A, the tab plate 14 is attached to the receptacle member 13. As described previously, the second portion 14 b of the tab plate 14 is folded twice to configure a U-shape cross section. The opening of this U-shaped second portion 14 b receives the third portion 13 c of the receptacle member 13. At that time, the latch 14 k, which comes in contact to the TOSA 15 and the ROSA 16, is set in the groove 13 n provided in the bottom of the U-shaped cutting. The tab plate 14 is assembled with the receptacle member 13 by engaging the latch tab 14 e with the projection 13 g in the side of the receptacle member 13.

2. Installing the OSAs in the Receptacle Member

Next, as shown in FIG. 4A, the TOSA 15 and the ROSA 16 are installed in the receptacle member 13. Respective OSAs, 15 and 16, provide a pair of flanges, 15 c and 16 c, in the head portion thereof, 15 d and 16 d, which is the so-called sleeve. These flanges, 15 c and 16 c, sandwich the wall 13 q therebetween that forms the U-shaped cutting. At that time, the tab plate 14 is sandwiched between the wall 13 q and one of the flanges in respective OSAs, 15 and 16. The width of the U-shaped cutting in the tab plate 14 is configured to be slightly smaller than the diameter of the sleeves, 15 d and 16 d. Accordingly, although the OSAs are easily set within the cutting by deforming the tab plate 14, the OSAs once set are hard to be disassembled. On the other hand, the width of the U-shaped cutting of the receptacle member 13 is slightly wider than the diameter of the sleeve, accordingly, to set the OSAs, 15 and 16, within the receptacle member 13 may be carried out without any problem. The tab plate 14 may configure an identification mark in the side where the TOSA is to be installed to distinguish the TOSA 15 from the ROSA 16. The assembly of the OSA unit 6 has completed after installing the OSAs, 15 and 16, in the receptacle member 13 with the tab plate 14. The OSA unit 6 is illustrated in FIG. 4B.

3. Installing the Substrate in the Base

Next, the primary substrate 17, on which the electronic circuit is mounted in advance, is to be assembled with the base 20. Prior to the assembling of the substrate 17, the thermal sheet 27 is put on the portion where the TOSA is to be mounted and the insulating film 19 is attached to the supplementary substrate 18 in the surface opposite to the surface the electronic component is mounted (FIG. 5B).

The primary substrate 17 is temporarily fixed with the OSA unit 6. This temporal fixing is carried out by putting the substrate 17 between the lead pins, 15 b and 16 b, when the OSAs, 15 and 16, provide the lead pins, without soldering. While, when the OSAs, 15 and 16, are connected to the substrate 17 with the FPC board, the soldering between the FPC board and the substrate, and between the FPC board and the OSAs, 15 and 16, may be carried out. Occasionally, the OSAs, 15 and 16, soldered with the FPC board may be connected or soldered with the substrate 17 after assembling the OSA unit 6 with the base. Some fixture to assist the assembly of the OSA unit 6 with the base 20 may be utilized in this process.

Sliding the rear part of the substrate 17 under the coupling surface 20 i of the base 20, the step 17 d formed in the side of the substrate 17 abuts against the side of the coupling portion 20 h, which automatically positions the substrate 17 on the base 20 in the longitudinal direction of the transceiver 1. Pressing down the substrate 17 as abutting against the coupling portion 20 h, the projection 20 k in the side 20 c of the base 20 fits in the notch 17 e formed in the side of the substrate 17. By configuring the width of the projection 20 k slightly wider than that of the notch 17 e, the relative position of the substrate 17 to the base 20 may be automatically and precisely determined. In such configuration, once fitting the substrate 17 in the base 20, the substrate 17 is hard to disassemble. A portion of the side 20 c of the base 20 is bent inward to stabilize the position of the substrate 17 put thereon.

Subsequently, the OSA unit 6 is set to the base 20, as shown in FIGS. 6A and 6B. Pressing the base 20 downward, as the OSA unit 6 is temporarily fixed with the substrate 17, the projection 13 m provided in the side of the OSA unit 6, practically provided in the side of the receptacle member 13, engages with the opening 20 a of the support 20 d. In the meantime of this engagement between the projection 13 m and the opening 20 e, the center post 20 f formed in the front end of the base 20 inserts into the opening 13 r in the center of the receptacle member 13. Thus, the OSA unit 6 is fixed to the base 20 by three positions, i.e., two positions in the side and one position in the front end thereof. Moreover, these three fixings are complementary to each other because the fixing in the side is between the convex in the OSA unit 6 and the concavity in the base 20, on the other hand, the fixing in the front end is between the concavity in the OSA unit 6 and the convex in the base 6. The bracket 25 is fit to the ROSA 16 after assembling the OSA unit 6 and the primary substrate 17 with the base 20.

4. Installing the Heat Conducting Plate

Next, the heat conducting plate 21 is installed on the base 20, which is illustrated in successive from FIG. 7A to FIG. 8B. First, the thermal sheet 24 is attached to the IC 17 c in direct thereto or via some resin material with flexibility and good thermal conductivity to enhance the heat conductance to the heat conducting plate 21. Subsequently, inserting the rear end portion 20 s of the base 20 into the opening between the surface 21 h and the spacer tab 211, of the heat conducting plate 21 and rotating the heat conducting plate 21 as touching the inner surface 21 s of the third portion 21 to the surface 20 r of the base 20, the surface 21 i fits to the front end 20 p of the coupling surface 20 i. Moreover, the spacer tab 211 widens the gap between the coupling surface 20 i while the legs 21 k put the tabs 20 j of the base 20 therebetween. That is, four sides, 21 s, 21 i and 21 k, surrounding the second portion 21 b of the plate 21 wrap and fit to the coupling surface 20 i of the base 20. The first portion 21 a of the plate 21 in the back surface 21 e thereof comes in direct contact to the thermal sheet 24 on the IC 17 c. The front legs 21 j of the plate 21 presses down the primary substrate 17 by fixing the plate 17 to the base 20.

Thus, the assembly of the heat conducting plate 21 with the base 20 may be carried out without any screws only by mechanically fitting of two members using the resiliency inherently attributed to metal materials. Therefore, the present transceiver has the configuration quite superior productivity.

The heat generated in the IC 17 c is conducted by the heat conducting plate 21 to the rear end of the transceiver 1, and finally dissipated to the cage 2 at the rear end surface 21 h. A substantial gap between the transceiver 1 and the cage is necessary to ensure the smooth insertion into/extraction from the cage 2. Therefore, even the heat generated within the transceiver 1 is effectively conducted to the cover 23; it is effective to radiate thus conducted heat to the cage 2. However, only the rear end of the transceiver 1 may touch to the cage 2 when the transceiver 1 is adequately set within the cage 2 and the plug of the transceiver 1 mates with the connector in the inner end of the cage 2. Accordingly, to conduct heat generated within the transceiver 1 to the rear end thereof may enhance the efficiency of the heat dissipation. The heat conducting plate adopted in the present transceiver 1 may provide a solution for the subject above mentioned.

5. Soldering the Lead Pins of the OSAs

Next, the lead pins, 15 b and 16 b, extending from the OSAs, 15 and 16, are soldered with the primary substrate 17. The processes thus described determine the relative position of the primary substrate 17 and the OSA unit 6 through the base 20, accordingly, the soldering, which is a type of the permanent fixing, between the lead pins, 15 b and 16 b, and the electrodes, 17 a and 17 b, on the substrate 17 may be carried out. The OSAs, 15 and 16, are necessary to position relatively to the receptacle member 13 to provide the optical receptacle 10 following the standard. On the other hand, the primary substrate 17 is necessary to position relatively to the covet 23 to ensure the smooth insertion into the electrical connector provided in the inner end of the cage 2. Thus, to connect the substrate 17 with the lead pins, 15 b and 16 b, in permanent after the positions of the substrate 17 and the OSAs, 15 and 16, may prevent the mechanical distortion from localizing in the soldering point.

When the bracket 25 is attached to the ROSA 16, the soldering between this bracket 25 and the ROSA 16 is also carried out simultaneously to the soldering of the lead pins, 15 b and 16 b. When the FPC board is used for connecting to the substrate 17, the soldering thereof may be optionally carried out after the assembly of the OSA unit 6. The flexibility inherently attributed to the FPC board can compensate the positional discrepancy between the substrate 17 and the OSA unit 6. The soldering for the electrodes, 17 a and 17 b formed on the primary surface of the substrate 17 may be carried out in the portion exposed between the heat conducting plate 17 and the tab plate 14, while through the opening 201 formed in the bottom 20 g of the base 20 for the electrodes in the back side of the substrate 17.

6. Installing the Supplementary Substrate

The supplementary substrate 18 connects to the one side edge of the primary substrate 17 with the FPC board 18 d, namely, the FPC board 18 d passes through the cutting portion 21 p of the heat conducting plate 21 to connect to the primary substrate 17. The supplementary substrate 18 is installed on the heat conducting plate 21 in the first portion 21 a thereof by folding the FPC board 18 d as the support post 21 m passes the opening 18 e in the supplementary substrate 18. Since the back surface of the supplementary substrate 18 exposes the interconnections, the insulating film 19 is put thereon, as shown in FIG. 5B.

The supplementary substrate 18, which is installed on the first portion 21 a, is fixed by the supporting plate 22, as shown in FIGS. 11A and 11B. The tip 21 j of the first portion 21 a of the supporting plate 22 is inserted under the second portion 21 b from the cutting 21 q as the fourth portion 22 d is lifted up. The first portion 22 a positions within the cutting 21 q, and the step 22 g in the leg 221 of the first portion 22 a fit to the notch portion 18 f of the supplementary substrate 18. Pressing down the second to fourth portions, 22 b to 22 d, the tab 22 i in the second portion 22 b abuts against the side of the support post 21 m, and the step 22 m in the leg 22 e of the fourth portion 22 d fits to the cutting 18 g of the supplementary substrate 18. Therefore, the supporting plate 22 is assembled with the heat conducting plate 21 and the base 20 by the step 22 g, the tab 22 i and the step 22 m. Setting the cover 23 to put the body unit of the transceiver 1 therein, the beam portion 22 k bent upward by about 0.2 mm abuts against the inner surface of the cover 23 such that the cover 23 presses this beam portion 22 k down, consequently, the supplementary substrate 18 is fixed to the heat conducting plate 21.

7. Assembling the Actuator

Next, the actuator 12 is attached with the transceiver 1 as shown in FIGS. 12B to 12D. The actuator 12, which is made of resin, is assembled with the receptacle member 13 with the axis 12 g thereof being fit to the beaked hook 13 f and the hollow 12 j receiving the center projection 13 e of the receptacle member 13. Sliding the actuator 12 on the bottom surface of the receptacle member 13 from the front side, the center projection 13 e is set within the hollow 12 j as deforming the beaked hook 13 f and the projection 13 e itself. In the same time, the axis 12 g is set within the beaked hook 13 f. Due to the tip shape of the beaked hook 13 f, the actuator 12 one set within the hook 13 f is hard to disassemble, namely, the actuator does not fall even the bottom of the transceiver 1 directs downward.

8. Setting the Cover

Prior to the setting of the cover 23, the thermal sheet 26 is attached, if necessary, to the portion of the TOSA 15 and the ROSA 16 exposed between the receptacle member 13 and the supplementary substrate 18. The thickness of this thermal sheet 26 is adjusted such that the top surface of the sheet 26 comes in directly contact to the ceiling of the cover 23 when the cover 23 is set to the body unit. The thermal sheet 26 may enhance the heat dissipating efficiency from the TOSA 15 and the ROSA to the cover 23. The heat thus conducted to the cover 23 may not only radiate to the cage 2 but also conduct to the rear end of the cover 23 and may be conducted to the inner end of the cage 2.

The cover 23 configures the latch tab 23 f with an opening in both front sides thereof, as shown in FIG. 14A, while, forms the stopper 23 h in the rear end. The opening provided in the latch tab 23 f is to be engaged with the projection 13 g provided in the side of the receptacle member 13. The cover 23 is set to the body unit such that the stopper 23 h abuts against the outer side portion 21 u of the rear end surface 21 h. The fin 23 d in the front bottom of the cover 23 extends forward, and the projection 12 e formed in the actuator 12 protrudes from the opening 23 e in the root of this fin 23 d. The fin 23 d supports the actuator 12.

As shown in FIG. 1, on the upper surface of the cover 23 is configured with the structure with two slits and the portion 23 c between these slits being bent inward. This bent portion 23 c comes in contact to the upper surface 21 r and the abutting surface 21 in of the heat conducting plate 21 to press the plate 21 downward. Since this bent portion 23 c has an arched shape, it makes no problem for setting/removing the cover 23 from the body unit.

9. Installing the Bail

The bail 11 is attached to the receptacle member 13. The projection 13 d in the side wall of the receptacle member 13 inserts into the opening 11 c formed in the leg portion 11 b of the bail 11, as shown in FIGS. 13A and 13B. The attachment of the bail 11 can be easily carried out by spreading the leg portions 11 b in outward. Setting the actuator 12 in the neutral position, the inner and outer sliding surfaces, 12 i and 12 h, is put between the cam surface 11 f and the sliding surface 11 h in the tip 11 g of the leg 11 b. The projection 12 e of the actuator 12 can be simply pulled inward by rotating the bail 11 or by pressing the front end 12 d of the actuator 12 downward, which may release the transceiver 1 from the cage 2.

Finally, labels, 28 a to 28 c, are stuck on the top and side surfaces of the transceiver 1 to complete the assembly. The label 28 a on the top surface may be covered by a transparent film 28 d to prevent thereof from peeling off by the insertion/extraction of the transceiver 1 to the cage 2.

The configuration and the assembling process of the present transceiver are thus described with referring to accompanying drawings. Since the present transceiver 1 assembles metal components made by cutting, bending or tapping the single metal plate and fits these metal components without any screws or other joining means, the cost not only the components themselves but also the assembling process can be reduced. Moreover, since the present transceiver 1 provides the heat conducting plate to dissipate heat from the IC 17 c installed in the center of the transceiver 1 to the outside thereof, besides the heat conducting plate made of copper alloy, the heat dissipation efficiency can be enhanced for the transceiver 1 to be apply to the high speed application over giga-hertz frequency band.

The optical transceiver according to the present invention provides, in addition to the fingered structure of the front end of the base 20, a shield member 40 to enhance the EMI tolerance. By setting the shield member 40 in the second necked portion, 15 f or 16 f, of the OSA and electrically makes a portion of the shield member 40 contact with the tab plate 14 and the base 20, a gap inevitably induced between the base 20 and the OSA may be effectively covered to enhance the EMI characteristic of the transceiver 1. FIGS. 19A and 19B show the shield member 40 viewed from the front (FIG. 19A) and from the rear (FIG. 19B). This shield member 40 is also made of metal plate, such as stainless steel, only by cutting and bending.

The shield member 40 includes planes, 40 b and 40 c, by bending the original plane 40 a at the upper side thereof. For the bottom side, the plane 40 a is folded twice so as to wrap the tip of the plane 40 c to form the plane 40 h and a plurality of fingers 40 d, three fingers in this embodiment. Another finger 40 e protrudes from the plane 40 a to a side opposite to the plane 40 h. Two U-shaped cuts formed in the plane 40 a correspond to the U-shaped cut formed in the receptacle member 13 and the tab plate 14. The width W of thus U-shaped cut is narrower than the width of the U-shaped cut of the tab plate 14 and wider than the diameter of the second necked portion, 15 f or 16 f, of the OSA because this shield member 40 is set in the second necked portion, 15 f or 16 f, and the diameter of this second necked portion is smaller than that of the first necked portion, 15 e or 16 e, as shown in FIG. 16. Thus, to set this shield member in the second necked portions, 15 f and 16 f, does not define the relative position of the shield member 40 with respect to the OSA or the receptacle member 13.

FIG. 20A shows a process to assemble this shield member 40 with the TOSA 15 and the ROSA 16, they are already built with the receptacle member 13 and the tab plate 14. FIG. 20B is plan view of the transceiver 1 after assembling the shield member 40 with the OSA unit 6 before assembling the OSA unit 6 with the base 20. The shield member 40 is set as the plane 40 b thereof faces up, where a surface not appeared in FIG. 20A corresponds to the top surface of the transceiver 1, and stuffed until the plane 40 b abuts against the bottom surface 14 i of the tab plate 14. In such arrangement, the tip of the fingers 40 d does not come in contact to the necked portions, 15 e and 16 e, of the OSA. As explained, the fingers, 20 t to 20 v, of the base 20 abuts against and holds the OSA in the first necked portions, 15 e and 16 e. It is unfavorable that this finger 40 d of the shield member 40 abuts against the OSA because it causes an excess stress being applied to the OSA.

The horizontal position of the shield member 40 is determined by the edge 40 f in the plane 40 h thereof touching to the outer wall of the U-shaped cut of the receptacle member 13. That is, when the shield member 40 is inserted into the second necked portion, 15 f or 16 f, of the OSA, and abutted the top of the member 40 against the bottom surface 14 i, to make the edge 40 f of the plane 40 h in contact to the edge of the U-shaped cut of the tab plate 14 defines the horizontal position of the shield member 40, and such arrangement does not make the tip of the finger 40 d in contact to the OSA although the finger 40 d is set within the first necked portions, 15 e and 16 e. Thus, only the finger positioned in outermost has a function to position the shield member 40 with respect to the OSA unit 6.

The base 20 is built with the OSA unit 6 after setting the shield member 40 in the second necked portions, 15 f and 16 f, as described. The center post 20 f of the base 20 mates with the socked 14 n of the tab plate 14 and the opening 20 e in the side 20 d of the base engages with the projection 13 g in the side of the receptacle member 13. In this arrangement, the fingers, 20 t to 20 v, in the front end of the base 20 pushes the first necked portions, 15 e and 16 e, of the OSA to position the OSA with respect to the receptacle member 13. Moreover, the protruding finger 40 e of the shield member 40 comes in contact with the rib 20 q of the base and both edges 40 i comes in contact to respective sides 20 d of the base 20, which secures the electrical contact between the base 20 and the tab plate 14. FIG. 20B also shows positions, to which the front fingers, 20 t to 20 v, of the base 20 is set, by hatched areas.

Thus, by setting the shield member 40 according to the present invention in the necked portion of the OSA and securing the electrical contact between the base 20 and the tab plate 14, the shield member 40 can effectively cover a gap induced between the base 20 and the OSA, when the transceiver is viewed from the front of the transceiver, which enhances the EMI characteristic. 

1. An optical transceiver, comprising: an optical subassembly having a pair of flanges and first and second necked portions, the first necked portion being arranged between the pair of flanges; a receptacle member having a U-shaped cut where the first necked portion of the optical subassembly is set therein; a tab plate made of metal and put between the receptacle member and one of the pair of flanges of the optical subassembly; a substrate for installing an electronic circuit that electrically communicates with the optical subassembly; and a base having a primary surface for installing the substrate thereon, the base providing a finger in a front end portion thereof, wherein the finger secures the first necked portion of the optical subassembly to set the first necked portion within the U-shaped cut of the receptacle member.
 2. The optical transceiver according to claim 1, wherein the finger is bent from the primary surface of the base, and wherein a tip shape of the bent portion of the finger traces an outer shape of the first necked portion of the optical subassembly.
 3. The optical transceiver according to claim 1, wherein the finger is divided in a plurality of fingers each bent from the primary surface of the base, and wherein at least one of the fingers extrudes more than the other of fingers to form a gap between at least one of the fingers and the other fingers.
 4. The optical transceiver according to claim 3, wherein an envelope curve of a tip of the bent portion of the fingers traces an outer shape of the first necked portion of the optical subassembly.
 5. The optical transceiver according to claim 3, further including a shield block made of electrically conducting material and set between at least one of fingers and the other of fingers.
 6. The optical transceiver according to claim 1, further comprising a shield plate made of metal and set within the second necked portion of the optical subassembly.
 7. The optical transceiver according to claim 6, wherein the shield plate comes in electrically contact with the base and the tab plate to shield the optical transceiver.
 8. The optical transceiver according to claim 1, wherein the tab plate and the base are made of metal plate only by cutting, bending and extruding, and wherein the tab plate provides a socket and the base provides a post in the front end thereof, the post being mated with the socked of the tab plate.
 9. The optical transceiver according to claim 8, wherein the base provides a side with an opening and the receptacle member provides a projection in a side thereof engaged with the opening of the side of the base.
 10. The optical transceiver according to claim 8, wherein the receptacle member is made of resin coated with metal. 